Knife shaft



FIG. 1 is a left side perspective view of the knife shaft showing our new design;

FIG. 2 is a bottom left side perspective view thereof;

FIG. 3 is a left side elevational view thereof; and,

FIG. 4 is a right side elevational view thereof.

The broken lines in the drawings which define a knife blade form no part of the claimed design. 

CLAIM The ornamental design for a knife shaft, as shown and described. 